1. Industrial Field of Application
The present invention relates to a fuel injector to be used for the fuel feed in an internal combustion engine or the like and, more particularly, to a fuel injector which is excellent in the fuel injection characteristics such as the angle, dispersion and atomization of a spray and which can inject and feed a fuel spray having a flat sector shape.
2. Related Art
The fuel injector, as used in the prior art for feeding the fuel to the internal combustion engine, is exemplified by a hole nozzle type or a throttle nozzle type. These fuel injectors are employed to inject and feed a conical fuel spray and are insufficient in the angle, dispersion and atomization of the spray. A variety of trials have been made to improve the insufficiencies.
For example, there is a multi-holed nozzle type fuel injector having elliptical slit-shaped nozzle outlets (as disclosed in Unexamined Published Japanese Utility Model Application No. 61-118969). However, this fuel injector does not note the width and length in the longitudinal direction of the slit-shaped nozzle outlets but is as insufficient in the angle, dispersion and atomization of the spray as those of the fuel injector of the prior art. These improvements are also required.
When this fuel injector is applied to a direct injection type internal combustion engine, as shown in FIG. 14, the spray has to be dispersed by a swirl S of the intake air into the regions d in a combustion chamber 22 where the spray injected from the fuel injector is not dispersed, so that the insufficient dispersion of the spray may be compensated by the swirl S. This makes it necessary to provide a suction mechanism such as a helical port for applying the swirl S to the intake air, and this suction mechanism increases a suction resistance to lower the output. When this fuel injector is applied to an injection type internal combustion engine, moreover, the injected spray is dispersed with a thickness in the axial direction of the cylinder. This makes it necessary to deepen the combustion chamber 22 and difficult to make the combustion chamber 22 compact. In addition, because of the poor dispersion of the spray and the excessive penetration of the spray tip, much fuel sticks to the wall face of the combustion chamber to deteriorate the combustion and to increase the soot in the exhaust gas and a variety of components necessary for purifying the exhaust gas.
Next, in a spark ignition type internal combustion engine for spraying and feeding the fuel, the slit-shaped nozzle outlet is formed into an elliptical shape, and the spray is branched in two directions by a pin at the leading end of a needle (as disclosed in Unexamined Published Japanese Utility Model Application No. 63-26769). However, this slit-shaped nozzle outlet is intended to reduce the stick of the fuel to the partition of the intake pipe branches. Moreover, the spray can be branched into the two directions by the pin at the leading end of the needle, but the atomization of the spray is insufficient. Because of the intense spray tip penetration, moreover, the stick of the fuel to the inner wall faces of the intake pipe is so much as to raise such a problem to be practically solved that the diffusion and mixing of the spray into the intake flow in the intake pipe is insufficient.
In the prior art, moreover, there is a fuel injector which is constructed to have an aspect ratio of the opening of the slit-shaped nozzle outlet at 4.5 or more (as disclosed in Unexamined Published Japanese Patent Application No. 3-78562). In this fuel injector, however, the angle of divergence of the fuel spray depends upon the depth of the inner end on the side of the inner circumferential wall of the fuel injector in the slit-shaped nozzle outlet so that a predetermined spray angle cannot be efficiently and properly sufficed due to the influences of the flow resistance.